Do I have tankless options?

[RidgebackKing]

I currently have a very old water heater in the crawl space (you can almost stand upright) under my house that serves the master bath, laundry room, and a half bath. It's able to serve a couple of concurrent showers but it just will not fill up the big jacuzzi tub. I was thinking a tankless water heater would be a great solution here but I'm not sure if one can be supported.

The breaker is a 30amp double pole with 10/2 wire to the disconnect.
Hot water at tub flows at ~7 gpm.
I do not have gas available.

Do those parameters allow for a tankless water heater capable of maintaining the flow rate or would I need to have an electrician give me an estimate on getting a higher amp connection to the install point, IF it could even be done? Thanks!

 

[Twowaxhack]

Ask the electric company relocate their power plant to your yard then you could go electric tankless.

But seriously, you don’t want an electric tankless.

Get another 30 amp circuit pulled and install two 50 gallon electrics side by side piped in parallel.


You’ll be good to go and always have one tank working at least !!!!!!

Trust me, I’ve done this at least once.....

 

[Twowaxhack]

If you have a bang up electrician there’s a way to run as many water heaters as you’d want to buy off that one 30amp circuit.

Recovery is twice as slow for two heaters with one 30 amp circuit but total hot water capacity is basically the same

 

[Twowaxhack]

I used a shroom because you’re located in Woodstock,Ga. ✌

You have any questions I’ll try to answer.

 

[RidgebackKing]

I used a shroom because you’re located in Woodstock,Ga. ✌

Are you thinking Woodstock 1969 in NY?

 

[FishScreener]

Electric tankless takes far more than 30-amps.

Second optionto two in parallel: Install a buffer thank, and a circulating pump. If the team in hte buffer tank drops, it turns on the circulator and pushes the colder water in the buffer tank, back the heater to get warm, and hotter water from the heater into the buffer tank.

Also, you can install a tempering valve on the outlet from the heater system, and crank the temp up. That way it gets down to safe temperatures at the taps, and by mixing cold with the hot, you get a higher yield before it cools off.

 

[Twowaxhack]

Electric tankless takes far more than 30-amps.

Second optionto two in parallel: Install a buffer thank, and a circulating pump. If the team in hte buffer tank drops, it turns on the circulator and pushes the colder water in the buffer tank, back the heater to get warm, and hotter water from the heater into the buffer tank.

Also, you can install a tempering valve on the outlet from the heater system, and crank the temp up. That way it gets down to safe temperatures at the taps, and by mixing cold with the hot, you get a higher yield before it cools off.

So you’re saying use a water heater as a holding tank and have a circ pump cycle on/off based off the holding tanks water temp.

This would circulate the cold water in the holding tank to the water heater that’s doing the heating.

That works too but that would require a pump and piping. It would tax the heaters elements doing double the work. Certainly will work though.

 

[sarg]

Just looked up the power requirements yesterday.
It's an amazing 120 amps for the average tankless electric ( three 40 amp breakers ) and 8 gauge wiring.
That's 60% of the normal 200 amp service ...... holy crap..

 

[Twowaxhack]

What most people don’t realize is the tankless manufacturers like to post the GPM as fact on their products. It’s presented that way until you read the fine print.

The fine print that talks about the incoming water temp.

Rate of rise is what you want to know.

How much volume of water can the water heater heat above the incoming waters starting temperature.

Then determine your coldest incoming water temp to the heater will experience.

 

[Twowaxhack]

Just looked up the power requirements yesterday.
It's an amazing 120 amps for the average tankless electric ( three 40 amp breakers ) and 8 gauge wiring.
That's 60% of the normal 200 amp service ...... holy crap..

The whole neighborhood dims when His family takes a shower.....

 

[RidgebackKing]

Just looked up the power requirements yesterday.
It's an amazing 120 amps for the average tankless electric ( three 40 amp breakers ) and 8 gauge wiring.
That's 60% of the normal 200 amp service ...... holy crap..

Yeah, I was hoping I was just finding whole house heater requirements but that doesn't appear to be the case. Even the "little" ones have hefty power requirements.

 

[RidgebackKing]

Also, you can install a tempering valve on the outlet from the heater system, and crank the temp up. That way it gets down to safe temperatures at the taps, and by mixing cold with the hot, you get a higher yield before it cools off.

Hmmm, this looks to be a very possible solution. Seems like I could basically double my capacity using a tempering valve. Does that seem about right?

 

[Twowaxhack]

Hmmm, this looks to be a very possible solution. Seems like I could basically double my capacity using a tempering valve. Does that seem about right?

There are draw backs to this. The hotter the water the more corrosive it is. When you go above 140 it snowballs.

Above 140 the minerals in the water start precipitating out and collecting in the tank. You won’t double your capacity using a tempering valve.

 

[Twowaxhack]

Let me give you something to go by.

If you wanted 110 degree bath water the percentage of hot to cold would be right at 52% hot water to cold water ratio with a cold water temp of 55 degrees and hot water temp in the heater of 160 degrees. Hot as a $2 pistol

So if your 50 gal electric water heater will deliver 35 gallons (70%) of its total capacity at the thermostat setting you can figure out how many gallons of standby water you need based on the size tub you’re filling and estimated other hot water use she in the home.

For every 5 degrees of desired outlet temp increase the hot water to cold water ratio goes up by approximately 6 percent. The transverse is also true, for every 5 degrees decrease in temp the hot water to cold water ratio decreases by approximately 6 percent


You still with me bro ?

If my wife kicks me out can I come live with you guys in Georgia? I’ll make sure we have plenty of hot water. I’m not sick.....

 

[RidgebackKing]

You still with me bro ?

I with you. If I wanted ~105 temp and had 140 degree hot water and 55 degree cold water, I'd need a 3:2 ratio. Which means if I wanted 100 gallons of it, I'd need 60 gallons of the hot water, or an 85 gallon tank. I don't think that'll work as there's not enough height for a tall tank and the entrance isn't big enough for the width of a short tank with that capacity, if they even exist

So it sounds like my choices are either 2 40/50 gallon heaters or an electric tankless. I was looking at the tankless as I really don't want to keep 2 water heaters (or 3 if you count them all) hot all the time.

Another crazy idea. The rest of the house is on another WH. Any way to connect the hot water lines with a one-way valve that I can open/close remotely?

 

[FishScreener]

I think the temperature change is based on degrees Rankin not Fahrenheit.

 

[Twowaxhack]

Get a propane tank installed and install a tankless heater. We do it here.....

 

[RidgebackKing]

I think the temperature change is based on degrees Rankin not Fahrenheit.

Isn't 1 degree Rankine the same as 1 degree Fahrenheit though? I thought Rankine was just Fahrenheit with an absolute zero of, 0.

 

[Twowaxhack]

Isn't 1 degree Rankine the same as 1 degree Fahrenheit though? I thought Rankine was just Fahrenheit with an absolute 0 of, 0.

I prefer not to unnecessarily complicate simple matters......

It’s all about how cold the incoming water is.....how hot you heat the water.....what volume of water your water heater will deliver at said temp and........lastly how much of said hot water do you need.....

Forget the rest.

 

[Twowaxhack]

I with you. If I wanted ~105 temp and had 140 degree hot water and 55 degree cold water,

That would require 59% hot water and 41% cold.

I have customers with 4 or 5 water heaters.....if the need is there. Big houses, detached apartments and garages with bathrooms. ETc....

The thing is that they last longer when they’re sized properly.,

When a water heater heats up it expands. When it’s cooled down it contracts. The tank is welded.....these welds fail.

This fatigues the metal and it fails. It doesn’t always have to be rust.

So lower temps and a larger supply contributes to a possible longer life of the water heater.